Dynamo-electric machine



March 23 1926. 1,577,948

J. a. BUSHNELL DYNAMO ELECTRIC MACHINE Filed Feb. 27. 1922 2Sheets-Sheet 1 7 f ATTokNEys March 23 1926.

J. 'B. BUSHNELL DYNAMO ELECTRIC MACHINE Filed l-eb. 27, 19 2Sheets-Sheet 2 WITNESS INVENTOR JOHN J. MJH/VELL 8 BY 47' M$J 15 4aATTORNEYS Patented Mar. 23, 1926.

UNITED STATES PATENT ()FFICE.

JOHN B. BUSHNELL, OF BERKELEY, CALIFORNIA, ASSIGNOB TO N. R. HARRIS ANDM. C. HARRIS, COPARTNERS, DOING BUEINESS AS HARRIS ELECTRIC COTMPANY,

OF SAN FRANCISCO, CALIFORNIA.

DYNAMO-ELECTRIC MACHINE.

Application filed February 27, 1922.

To aZZ 1071 0772 it may concern:

Be it known that 1, JOHN B. BUsI-INELL. a citizen of the United States,and a resident of the city of Berkeley, in the county of Alameda andState of California, am the inventor of a new and useful Dynamo-ElectricMachine, of which the following is a specification.

This invention relates to a dynamo electric machine, and moreparticularly to an inductor generator. Such generators are now usedextensively in automobile lighting equipment, and are arranged to bedriven from the shaft of the engine. Since the engine speed necessarilyvaries considerably, the generator is so arranged that speed variationsdo not cause its operating characteristics to be varied materially. Thisresult has been obtained by various expedients, such as by working theiron in the magnetic circuit above the saturation point, by mahing thegenerating coil or coils have a relatively high resistance, or byutilizing the reaction of the current flowing in these coils upon themagnetic circuit. It has been found that the best regulating effects areobtained when the lights are all arranged in series on a single circuit;that is, when a straight series connection is used. This arrangement hasthe serious disadvantage that when any one of the lights happen to beout of order, the entire generator is disconnected and out of use. It isone of the objectsof my invention to make it possible for an enginedriven generator to supply a plu rality of circuits which are capable ofin dependent operation.

In order to obtain this result, I provide a single magnetic circuit inwhich there are a plurality of gaps in series, these gaps being bridgedby rotating inductors. With each gap or opening is associated one ormore generating coils, and I have found in such an arrangementthat thecircuits for any of these independent coils may be made or brokenwithout interfering materially with the operation of the other coils.This arrangement is very compact, since virtually a single magneticcircuit serves for the equivalent of a plurality of generators. It isthus another object of my invention to provide a generator havingrelatively small weight for its capacity.

Serial No. 539,387.

My invention possesses other advantageous features, some of which, withthe foregoing, will be set forth at length in the followingspecification where I shall outline in full those forms of the inventionwhich I have selected for illustration in the drawings accompanying andforming part of my present specification. In the drawings I have shownseveral embodiments of my invent-ion, but it is to be understood that Ido not limit 1nvself to those forms, since the invention as expressed inthe claims may be embodied in other forms as well. I

Referring to the drawings:

Figure 1 is a side view, partly sectional, of a complete inductorgenerator embodying my invention;

Fig. 2 is a sectional view taken along the line. Q-2 Of Fig. 1; i

Fig. 3 is adiagrannnatic view of the mag netic circuits of the generatorillustrated in Figs. 1 and 2;

Fig. a is a. diagrammatic view of a modification of my invention;

Fig. 5 is a diagrammatic view of a further modification;

Fig. 6 is a diagrannnatic view of the generator coils; and i Fig. '4' isa wiring diagram of a lighting system embodying my invention As is usualin inductor alternators, there is a magnetic circuit, part of which isstationary and a part movable. The movable portion is usually theinductor, and its move ment past the pole faces causes a variation inthe number of lines of force threading a generating coil. In themodification sl'nnvn in Figs. 1, and 3, a plurality of stationarypermanent bar magnets 11 is used to supply the magnetizingforce. Thesemagnets 11 have opposed pole tips 12, 1i and if), and are arranged inopposed relation to each other, as clearly shown in Fig. The mag nets 11are arranged to assist each other: that is, if the tip 12 forms a northpole, then tip 13 forms a south pole. In this arrangement a plurality ofgaps in series is formed in the magnetic circuit, in'which gaps arelocated the rotatable inductors 16 and 17. These inductors by theirmovementcause a variation in the magnetic lines of force threading thestationary generating coils 1S and 19, which are located in slots in thepole tips 12, 13, 1 1 and 15. The axes of coils 18 and 19 are at rightangles to the axes of rotation of the inductors 16 and 17, oppositesides of the coil being located in op posite pole tips. The slotsaccommodating these coils are purposely made wide enough to preventappreciable magnetic leakage between the two halves of the pole tips.Assuming rotation in a counter-clockwise direction, and that the poletip 12 forms a north pole while tip 13 forms a south pole, the directionof the flux threading coil. 18 will be downward. However, aftertheinductor has rotated through 90, into the position shown by thedotted lines, the direction of the flux will be reversed as regards thecoil 18. This reversal takes place when the inductor 18 leaves theposition opposite the upper part of tip 12 and takes a position oppositethe lower part of tip 12. he variation in the direction and amount ofthe magnetic flux induces an E. M. F. in the coil 18. Movement of theinductor 16 through another 9O will again reverse the flux for then aposition similar to the full line position is again obtained. The upperand lower portions of each of the pole tips extend through an arc ofsubstantially 45, and the slots formed in them also extend substantiallythe same amount. In this way the portions of the pole tips are uniformlyspaced around a circle, and complete uni form electron'iotive forcewaves are obtained for every half-revolution.

The generation of an electromotive force in coil 19 is produced in amanner entirely similar to that already described in connection w'thcoil 18. Coils 18 and 19 may, if desired, be connected to the same load,or they may preferably be used to supply separate lamp loads. Thus eachheadlight lamp may be supplied with current from separate coils. In thisway, the two headlight lamps may be independently controlled oroperated. Preferably the two inductors 16 and 17 are driven at the samespeed, usually by the engine shaft. These inductors may be displacedrelatively to each other, as indicated in Fig. 3, so that while one ofthem does not serve as a good magnetic bridge between the pole tips, theother one is in the proper position for conducting the lines of forcefrom one tip to the other. In this way there is never more than onelarge air gap in the magnetic circuit, and therefore the same magneticstrength is obtained as if there were but one inductor and but one gap;thus while inductor 17 is horizontal, and not serving to conduct linesof force from one pole tip to the other, the inductor 16 is in such aposition that it connects the upper portion of pole tip 12 with thelower portion of pole tip 13. The same magnetic circuit. isadvantageously used for a pluraiity of generators, producing E. M. F.s

that are out of phase with each other, and there is an attendant savingin the cost and size of a machine for a given output.

However, since the current in the generat ing coils' necessarily lagssomewhat behind the elect'romotive force due to the self induction ofthe circuit, one of the two coils 18 and 19-acts at certain portions ofa cycle, to assist the building up of magnetism in the magnetic circuit.As a matter of fact, the balancing of the various magnetomotive forcesis such, due to saturation effects and the reaction and resistance ofthe coils, that even upon a wide range in engine speed or in theresistance of the external circuit, substantially the same currentoutput is obtained. The theoretical analysis of the. rcgulative action.is obviously so complex that no atten'ipt will be made here to discussit.

The actual mechanical embodiment of the form of my invention describedhereinbcfore is shown to best advantage in Figs. 1 and 2. The inductors1G and 17 are each mounted on shafts suchas 20 which are supported inroller or ball bearings carried by the housings 21 and 22. Each of theshafts carries a pinion 23 securely fastened to the shaft, with which agear 2% is arranged to mesh. This gear rotates about an axis coin cidentwith that of the shaft of the machine, which is adapted to be driven bythe engine. This shaft is appropriately journaled in the housing members26 and 27, which encase all of the operatin parts of the generator. Themember 2: is itself split lengthwise for ease in assembling andmanufacture. The driving connection between the shaft and the gear 24;includes a. friction clutch 28, one part of which is slidably butnon-rotatably mounted upon the shaft 25, and the other part is madeintegral with a hollow sleeve-like member 29 encompassing the shaft.This member 29 is securely fastened to the wheel 24-, and itselfjournaled for rotation in an aperture or bore formed in the interior ofcasing member 27. The fastening of member 29 to gear 21%. may beaccomplished in any appropriate manner. For example, a bushing 51 havingan exterior surface journaled in frame 27 can be fastened to member 29by the aid of the key 52, and gear 2a may likewise be held on member 29by the aid of this key. In order to prevent axial movement of parts 2 1and 51 a ring can be used, held to sleeve 29 by a set screw 49.

The clutch faces on parts 29 and 30 may be made to engage or disengageby means of a lever 31, fastened to a shaft 32 which is pivoted withinthe casing member 26. This shaft carries a fork 33 which engages withinthe groove 34 of the member 30 so as to slide it axially upon the shaft25.

The permanent magnets 11 are conven;

iently supportedin the member 27, in panell ilre pockets formed by theribs 35. The pole tips 12, 13, 1% and are imbedded in this casing memberalso, as shown most clearly in Fig. 2. This casing member must of coursebe made or"- non-n'iagnetic material so that the magnetism will not beshunted in'iproperly by it. The coil 18 is made in two sections and theend portions of these sections are turned up at right angles from theside portions \vhich fit into the slots in the pole pieces. A diagram ofthe coil is illustrated in Fig. 6, the parallel sides 36 forming theactive part of the coil.

The casing members 26 and are apnopriately fastened together as by thebolts 37, and the arrangement is such that a compact, practicallydust-proot covering tor the working parts is obtained.

The important conception of utilizing a single magnetic structureserving as a seres magnetic circuit for a plurality of generating unitsmay readily be extended to accommodate even dissimilar units. Thus inFig. t, in addition to the two inductor type units 38 and 39, a hightension magneto unit 10 may be placed in the same magnetic circuit. hislatter unit may have a wound rotatable armature member 41, and may beused, for example, for the ignition circuits of the gasoline engine. itused in this way, the unit 40 must have its armature rotated at the samespeed as the engine shaft.

sinother embodiment oi my invention, in which three inductor generatorunits are used, is diagrammatically shown in Fig. 5. It is of courseevident that the units using the same magnetic circuit in series may bedissimilar in size or kind, the better to fit each of them for theservice demanded.

Thacaptation of my iivcntion in an automobile lighting system producescertain beneficial results. Such an adaptation is illustrated in theWiring diagram of Fig. 7. Here the generating coil 18 is connected tohead light &2 and tail light as, While another generating coil 19 isconnected to the other headlight L3 and another tail light T5.Appropriate connecting devices i6 and all located in a convenientposition may also be supplied. The magnetic circuit or the generator isomitted from the drawing, and

instead the rectangle t8 is intended to reprcsent the completegenerator.

in a system such as illustrated in this figure, the total tailure of thelighting tcm is highly improbable. There is furthermore no danger thatthe tail light will not be lit, so long as one oi the headlights is inoperation.

I claim:

l. in an inductor alternator, a pair of magnets having their unlikepoles arranged opposite each other, means forming poles near theextren'iitics oi the magnets so as to "form two gaps in cries, amagneticrotor in each gap. and windings associated with the inaguetic structure.

2. Tn an inductor alternator, a pair Of magnets having their unlikepoles arranged opposite each other, slotted pole tips carried near archextremity of the magnets so as to form tvso gaps in series, a rotatableinductor in each of the gaps, and generating coils disposed in the slotsin the pole tips.

in an inductor alternator, a pair of sets of permanent DIHQ'DQJSarranged opposite each other, pole tips carried at each extremity of themagnets so as to form two gaps in series, a rotatable inductor in each 6of the gaps, and coils disposed in slots to 1 10d in the pole tips.

4:. In inductor alternator, a pair of sets of permanent magnets arrangedopposite each other, pole tips having slots carried at each extremity otthe magnets forming tvro gaps in series, a coil associated with eachgap, and a rotatable inductor in each gap.

5. In an inductor alternator, a pair of sets of permanent magnetsarranged opposite each other, pole tips having slots carried at eachextremity of the magnets forming tvvo gaps in series, a coil associatedwith each gap, inductors mounted for rotation Within the gaps, and acommon means for rotating both inductors, said inductors being soarranged that the electromotive forces generated in the coils are out ofphase with each other.

in testimony whereof, I have hereunto set my hand.

JOHN B. BUSHNELL.

